The present invention belongs to the field of the light modules comprising a laser source. In particular, it relates to a device and a method for securing such a light module.
The present invention is particularly advantageous when it is implemented in a light-emitting device incorporated in a vehicle and comprising the light module.
A “light-emitting device” should be understood to be any device capable of emitting light. For example, a headlight or a light of a vehicle, a pocket lamp, a lamp incorporated in the interior of a vehicle, a nightlight incorporated in a seat of a train wagon, a component of a television screen or even a high-intensity searchlight on a coastguard boat are examples of light-emitting devices. A vehicle should be understood to be any type of device capable of moving, such as a car, a truck, a scooter, an airplane, a train or even a sled.
A “light module” should be understood to be any sub-device of the light-emitting device from which the light is emitted. Thus, the light module can comprise a light source.
A “laser source” should be understood to be any device capable of producing a spatially and temporally coherent radiation based on the laser effect. Hereinafter in the present description, the terms “laser source” and “laser” are used indifferently.
Depending on the power and the emission wavelength of the laser, the latter can represent a real hazard to sight and cause irreparable burns to the retina.
Nevertheless, the use of lasers is desirable in many products intended for the public. For example, in the motor vehicle industry, the lights and/or headlights of the vehicles comprising lasers are sought after for their performance levels (range, form of the beam for example) and their esthetic appearance.
FIGS. 1, 2A and 2B represent a known source module 1 comprising a processing module 8 capable of securing a laser beam emitted by a laser source 2. The source module 1 typically has a cylindrical form.
In particular, a laser beam 18 is generated by the laser source 2 that is then focused by a lens 6 after having passed through a flat glass 4. At the output of the lens 6, the beam is coherent, typically in a wavelength in the blue. At this stage, and through its coherence, the beam is dangerous. In effect, such a beam is called class 4, in the French standard NF EN 60825-1, i.e. the most dangerous class.
To make it possible to use such a laser beam in consumer applications, it has been proposed to process the laser beam 18 through a processing module 8.
The processing module 8 comprises a ceramic ring 10 having a reflecting coating, a pad 12 of photoluminescent material and a protective glass 14. The photoluminescent material is for example of YaG, yttrium-aluminum grenate, type.
As detailed in FIG. 2A, when the beam 18 which, on leaving the lens, is of class 4 and coherent, arrives on the pad 12, some of the signals forming the beam are converted to have a wavelength in the yellow. These converted signals are added together with the signals which have not been converted so that the resulting beam is no longer coherent. Thus, the beam leaving the processing module is no longer class 4 and can be used for a consumer application.
However, in some applications such as the motor vehicle industry, the processing module can be subject to impacts or other deteriorations. In this case, the pad 12 of phosphor can be damaged and show deteriorations 16, such as cracks or breaks. In this situation, illustrated in FIG. 2B, some beams like the beam 20A can still be correctly processed by the processing module 8. However, other beams cannot be correctly processed and therefore diffuse a very dangerous coherent laser beam 20B.